The Brazilians came from behind to secure a 2-1 win over the Urban Warriors as strikes from Ricardo Nascimento and Sibusiso Vilakazi cancelled out Fagrie Lakay's goal.
The victory has moved Sundowns four points clear of Cape Town City at the summit.
"It was a good response, they showed integrity. They showed that they have the experience to manage a game. We managed the game very well in the second half," Mosimane told SuperSport TV.
"We didn't play pretty football in the last 20 minutes, that's Champions League experience.
"I'm happy with the mentality you know, unlike when we play expansive in the last 10 minutes and then they get a break and score."
Mosimane also confirmed that the club will be making further signings in the current January transfer window but refused to comment on their pursuit of Jeremy Brockie.
"Yes, we were using this game for Champions League. I think three or four [players] will come," he added.
"Jeremy Brockie belongs to another club so I don't want to speak. I have to respect SuperSport United. So I can't talk about Jeremy.
"We might lose three [players] because it's a period of transfers. Unfortunately we have a small squad of 24 players, we don't have much. People know Sundowns having a lot of players but we have 24 outfield players and four goalkeepers. We want to see, Thela [Ngobeni] wants a break to go play somewhere. We are managing the situation."